The overall objective of this research program is better understanding of the human enzyme system involved in alcohol metabolism to find out whether any components of the system are different in the alcoholic. We have purified to homogeneity and characterized two human liver aldehyde dehydrogenases, E1 and E2. Purification and characterization of another human liver aldehyde dehydrogenase (E3) is now in progress. Only E1 isoenzyme is sensitive to disulfiram. Human liver also contains two more aldehyde dehydrogenases (E6- a soluble and E7- a membrane enzyme) which have to be isolated and characterized. Substrate specificity of E1 and E2 isoenzymes is being investigated and attempts are being made to develop antibodies to both isoenzymes. While human blood appears to contain isoenzymes electrophoretically identical with E1 and E2, human blood contains other molecular forms (E4 and E5) whose identity has to be established through interaction with anti-aldehyde dehydrogenase antibody. Attempts are being made to develop a two-dimensional system for identification of isoenzyme content and composition of human liver alcohol dehydrogenase, which consists of at least 10 isoenzymes superimposing with each other in one-dimensional systems. Our goals for the coming year include further characterization of human liver aldehyde dehydrogenases E1 E2 and E3 isolation and characterization of E6 and E7 isoenzymes and investigation of aldehyde dehydrogenase content and composition of organs other than liver. When two-dimensional electrophoresis for alcohol dehydrogenase is developed, alcohol dehydrogenase content and composition will be compared with that of aldehyde dehydrogenase in individual human livers. The results will be correlated with the individuals life history related to alcohol consumption.